How Drinking Gives You Double Vision

This week, Answer Fellas gets down to the science of those two Stephen Colberts on your TV

On the rare occasion that I have too many drinks, I get double vision. Why? It is particularly problematic watching late-night TV. Closing or covering one eye seems to fix it, so I'm considering getting an eye patch.

"It's clear that acute alcohol ingestion does cause double vision," Bruce Martin, a physiology professor at Indiana University, tells AF. "We think it has to do with the effects of the alcohol on the brain and the brain stem and the nerves that control your eye movements and tracking. It slows down the brain so you can't get the eyes tracking on something quickly. The time it takes to get your two eyes — their images — to fuse to give you a single image increases when you drink."

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Professor Martin adds that this increase in the time it takes both eyes to fuse an image is a far more urgent issue in your car than on your couch, depending on your roommate's level of drunken hostility. "When things are coming into your vision suddenly, you want to be able to figure out where they are and how fast they're moving — quickly."

Covering one eye can help, he notes, "because then you don't have your brain comparing the two images. You just have the one image." Which makes you a perfect candidate for an eye patch — or, if Jimmy Fallon's on, two.